Stop looking like that!

The disturbing thing is that that is the same expression they’d have on their face when they were ripping up a hadrosaur. Being a monkey-faced primate with a dependence on facial expressions really sets up inappropriate expectations when looking at stone-faced reptiles.

This is why I stopped keeping reptiles. As a kid I had various lizards and snakes. I couldn’t tell when they were sick or hurt. That was much easier with our family’s mammalian pets. Because they couldn’t grimmace or yelp when their jaw was broken, when their heating stone malfunctioned, because they couldn’t otherwise tell me when they needed help, they suffered terribly under my ‘care’. I’m sure I wasn’t alone, and I doubt the plight of reptilian pets has improved much.

On the other hand, it does show just how useful a Tyranosaurid‘s fore arms can be.

In Eggs, Nests, and Baby Dinosaurs: A Look at Dinosaur Reproduction (Carpenter, 1999) has a colour plate of a couple of Carnotaurus‘ coupling. And they have a look that, in a mammalian visage, would be one of pure joy.

Sad thing is this isn’t even the most debauched picture. The filters on the Pelecanimimus image make it look like the male is performing some kind of surprise ballistic butt-sex maneuver, and pentaceratops’ “cum-face” is something I could quite happily have lived my life without ever thinking about, let alone seeing recreated.

Why did so many palaeontolgists assume that sauropods were amphibious (c.f. Matthew, 1915)? Even now, when the evidence for fully terrestrial existence is accepted, someone insists that their sex had to be supported by water?

The Morrison Formation in the US West was a gently sloping plain with seasonally variable rivers running from (approximately) west south west to east north east. Nowhere on this plain were there really deep rivers or lakes. The rivers were fairly wide and shallow and whatever ponds or lakes there were were quite shallow. Yet this was an incredibly rich ecosystem in which the dominant herbivores are sauropods (Apatasaurus and Camarasaurus for example). Where did they mate if it had to be done in deep water? Jurrasic waterbeds?

Please note that the article that is getting sent around isn’t based on a technical study or anything of that sort. It is just the slow season of reporting, so someone hacked together information from Bev Halstead’s presentations from the 1980s</b. (!?!) and quotes of contemporary researchers from TV documentaries.

There actually have been decent technical studies of dinosaur copulation in a phylogenetic and biomechanical standpoint, such as:

Tell me I’m not the only one that got the ad for sex toys on the side of this article! That made me take a moment to log in to congratulate the ad choices randomly selected here. But the picture certainly did nothing to encourage *me* to buy sex toys!

I don’t have the book handy, so I cannot, at the moment, provide a cite, but the skulls of Tyranosaurids that I have seen show definate holes in the bones (dentary, maxilla, premaxilla) with holes for nerve(?) passage which would imply that there is a covering. Not necessarily long enough to cover the teeth, but they do appear to have had lips.

For a living example of dinosaurs mating, just watch birds, the living branch of the Dinosauria.

Bald eagles, for example, have a devil of a time: momma-to-be crouches down on a convenient perch with her tail to one side. Papa-to-be flutters above and behind while they engage in a “cloacal kiss”. Lots of squawking from papa before and during. Over and done with in seconds.

The key curiosity here is the combination “bald eagle” and “flutter”. Sparrows flutter, but bald eagles??? It’s really a very awkward process. In most birds, copulation is not penetrative. There’s another reason for not letting those faux-smiles fool you into thinking that dinosaurian mating is like primate mating.

For that matter, any farm yard with chickens can be used to study dinosaurian mating as long as there’s a rooster among the flock.

@FossilFishy: Birds FTW as well. Though I’m sure non-avian dinosaurs would manage as the base of the tail was relatively flexible.

@Ogvorbis: They wouldn’t be particularly useful in that posture nor for anything afterwards: pronated hands are a big anatomical no-no for dinosaurs. Might this be the image you were mentioning ( http://www.luisrey.ndtilda.co.uk/jpegs/256col/carnsex1.jpg ).
Here’s a knowledgeable discussion on the subject of dinosaur lips. In my work I tend towards croc lips as the phylogenetic signal among Ornithodira is developing beaks at the (comparative) drop of a hat, which squamates AFAIK never have done.

@fredsalvador: If it means I’ll have to see one less image of a charging dinosaur roaring in rampage I’ll gladly accept this so-called debauchery. At least they are gaping their mouths with good reason. Besides, “surprise butt-sex maneuvers” aren’t unheard of in nature: I’d suggest checking out the moves on deers and sparrows.

Are they stone faced reptiles? The male in the depiction, clearly has what appears to be feathers on his back and his leg that he’s gaining purchase with looks curiously like a very large chicken leg from KFC.

I remember seeing the “sauropod had to stay in water to support their bulk” thing when I was in elementary school, five decades ago. I was under the impression it had been debunked almost as many decades ago!

Tell me I’m not the only one that got the ad for sex toys on the side of this article!

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I recently learned that T. rex lacked lips

Still under discussion, and more likely wrong than not if you ask me.

In most birds, copulation is not penetrative.

Because most birds belong to a clade that has lost the penis. Having one is the ancestral state.

In my work I tend towards croc lips as the phylogenetic signal among Ornithodira is developing beaks at the (comparative) drop of a hat, which squamates AFAIK never have done.

That’s probably because squamates lack the caruncle and use the egg tooth instead. Once the caruncle – a keratinous structure used to open the eggshell from the inside – has been lost, it’s apparently impossible to evolve a beak.

In case you were wondering, paleontologists believe T. Rex and friends mated much like dogs do.

“All dinosaurs used the same basic position to mate,” Beverly Halstead, an English researcher considered a pioneer in the subject of dino sex, told the Daily Mail. “Mounting from the rear, he put his forelimbs on her shoulders, lifting one hind limb across her back and twisting his tail under hers.”

I haven’t read further than this, because the ‘author’ of this piece of crud is clearly stupid. The described method of mating is like birds and lizards, NOT like dogs at all! D:

@3-

I couldn’t tell when they were sick or hurt.

You… couldn’t? I was able to tell when my female anole went blind when I was a kid and for three months I hand fed her decapitated meal worms dusted in calcium and gave her water several times a day. She maintained good weight for those months, and then one morning she had died. She was close to 6 years old at that point.

With my snakes I can still tell if they are sick or injured. Burns and infection show up as dry/crinkled scales or washes of pink where there should be none. Respiratory infections show up early with mouth gaping and progress to sneezes and hissing breaths. If a normally active snake is now huddling under a hide and is NOT due to shed there’s something wrong. I know the simple personalities of all my critters and if one acts out of the norm I take it with me to work to have the reptile vets look it over.

Do we know the relative orientation and positioning of the dino vagina?

Behind the pelvis, as in all vertebrates where this applies.

The trick about mammals is that the tailward pair of pelvic bones (ischia) don’t touch in the middle, allowing the genitals to move forward till they hit the bellyward pair of pelvic bones (ossa pubis).

David Marjanović: Yeah, I read something about Tyrannosaurs lacking lips. I subsequently decided that it was bollocks. Also, whats with the feathers? I haven’t seen any articles that indicate that Tyrannosaurs retained feathers into adulthood.

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Also, “ballistic butsex” person: you owe me a new keyboard, preferable one now drenched in Ardbeg.

A.R.: We honestly do not know the integument of large-bodied tyrannosaurids at present. Back in the old days (of 2011 and earlier…) we could speculate that large-bodied forms may have lacked feathers as they would not need them for insulation given their small surface area/volume ratio. But now with the discovery of 1 tonne Yutyrannus, we have basal tyrannosauroids with fairly extensive fuzzy covering.

The few patches of skin impressions of derived tyrannosaurids preserved show extremely small pebble-like scales or no particular scales. However, said specimens are preserved in a mudstone too coarsely grained to preserve simple protofeathers.

So given that: a) large derived Tyrannosauridae like T. rex are deeply nested within known fuzzy dinosaurs and b) where the integument is known, more basal large-bodied tyrannosauroids have said fuzz, we cannot at this time reject the possibility of fuzzy adult Tyrannosaurus and company.

Thomas Holtz: Interesting. I haven’t really kept up with the paleontological literature since 2010, so this is all quite fascinating to me. My one wish is that someone will find some crazy preserved (or fragmentary) paleovirus for me to play with in my lab!

What I’ve always thought was odd is that T Rex is always shown with all its teeth in some kind of death’s head leer. Surely they would have had, if not lips, then skin to hold their mouths closed. I don’t know of any reptiles where all their teeth are always showing on the outside. Crocodiles and alligators are the closest examples I can think of but even they don’t have all their teeth constantly exposed. And no I’m not changing the subject.

BTW, there is an as-yet unpublished paper on evidence for and against dinosaurian lips by paleoartist Tyler Keillor presented at a conference several years ago; hopefully it will see the light of day sometime in the near future.